In a normal field of vision, the two eyes perceive views of the world from two different perspectives due to their spatial separation within the head. The images from these two perspectives are then recognized as a stereoscopic image by the brain due to parallax of the two images. By utilizing this principle, there has been developed a liquid crystal display in which 3D (three-dimensional) display is carried out by parallax generated by causing an observer to see images from two different points of view through the right eye and the left eye, respectively.
In some 3D liquid crystal displays, images from different points of view are supplied to the respective eyes of the observer by first encoding the left eye image and right eye image on the display screen according to e.g. color, polarization state, or display time, and then separating these images through a filter system of glasses worn by the observer. In this way, only images intended for the respective eyes are supplied to the left eye and right eye of the observer.
In other liquid crystal displays, a display panel 101 is combined with a parallax barrier 102 having a light-transmitting region and a light-shielding region arranged in a stripe pattern. This allows an observer to recognize a 3D image without using a visual assistance such as the filtering system (autostereoscopic display). Specifically, a parallax barrier 102 gives specific viewing angles to the right eye image and left eye image generated by the display panel 101 (see FIG. 11(a)). When viewed in a specific spatial viewing range, only images intended for the respective eyes are viewed by the observer, and a 3D image is recognized (see FIG. 11(b)).
Such a liquid crystal display device that carries out autostereoscopic display by using the parallax barrier is disclosed in U.S. Pat. No. 6,055,013 (Date of Patent: Apr. 25, 2000), for example. In U.S. Pat. No. 6,055,013 (Date of Patent: Apr. 25, 2000), a patterned retardation plate is used as the parallax barrier.
Such a liquid crystal display device employing a parallax barrier is also disclosed in U.S. Pat. No. 6,046,849 (Date of Patent: Apr. 4, 2000), for example. In the liquid crystal display disclosed in this publication, 3D display and 2D display (two-dimensional display) are electrically switched by providing a switching liquid crystal layer or the like as a means of activating and inactivating the effect of the parallax barrier. That is, in accordance with ON/OFF of the switching liquid crystal layer, the display of U.S. Pat. No. 6,046,849 (Date of Patent: Apr. 4, 2000) performs 3D display when the effect of the parallax barrier is activated, and performs 2D display when the effect of the parallax barrier is inactivated.
However, the following problems arise in the conventional 2D/3D switching liquid crystal display devices.
Such a 2D/3D switching type liquid crystal display device carries out the 3D display by allowing emitted light, from a light source, to pass through three active areas: the switching liquid crystal layer, the parallax barrier, and a display liquid crystal layer (liquid crystal layer on which a display image is generated). Therefore, the 2D/3D switching type liquid crystal display device is realized by a transmissive type liquid crystal display device.
Meanwhile, while the 2D/3D switching type liquid crystal display device carries out the 2D display with the parallax barrier deactivated by the switching liquid crystal layer, emitted light from the light source also passes through the three active areas (the switching liquid crystal layer, the parallax barrier, and the display liquid crystal layer) in the same manner as during the 3D display.
Because the 2D/3D switching type liquid crystal display device carrying out the 2D display includes the switching liquid crystal layer and the parallax barrier, the 2D/3D switching type liquid crystal display device have a thicker liquid crystal display panel than a device carrying out only 2D display (hereinafter, 2D display by such a device is referred to as “2D-only display”). Therefore, even when the observer obliquely views the display screen of the 2D/3D switching type liquid crystal display device from a point within the viewing angle secured by the display liquid crystal layer, the other components (i.e., the switching liquid crystal panel and the parallax barrier) possibly prevent recognition of an image displayed on a peripheral portion of a display area of the display liquid crystal layer. In other words, this narrows the viewing angle, which ensures recognition of the entire display area of the display liquid crystal layer, as compared with the viewing angle of the 2D-only display.
Further, in the 2D/3D display liquid crystal display device having such a structure, a display liquid crystal panel requires, outside of its active area, a region for a terminal section for input and output of electric signals (a scan signal and a data signal). Moreover, a switching liquid crystal panel is required to receive a signal (switching signal) for electrically switching optical properties of the switching liquid crystal layer. Therefore, a terminal section for receiving the switching signal is also required to be provided outside the active area of the switching liquid crystal panel.
On the other hand, because the patterned retardation plate serving as the parallax barrier is not required to receive such electric signals, a substrate of the patterned retardation plate does not essentially require any area other than its active area.
Accordingly, because substrates of the display liquid crystal-panel and the switching liquid crystal panel are provided with the terminal sections, the substrates are larger than the patterned retardation plate by sizes of the terminal formation portions, respectively. Therefore, the terminal formation portions of the display liquid crystal panel and the switching liquid crystal panel protrude from a 2D/3D switching type liquid crystal display panel constructed by assembling the display liquid crystal panel, the patterned retardation plate, and the switching liquid crystal panel.
Because the terminal formation portions thus protrude from the 2D/3D switching type liquid crystal display panel, and are portions of the substrates made of glass, the terminal formation portions tend to be easily broken by external stress. For example, the glass substrates are cracked by the external stress, such as dropping and impact, exerted on the terminal formation portions. This causes the liquid crystal display panel to, e.g., be out of display action. Such a problem is particularly serious for liquid crystal display panels for a mobile phone and a PDA (Personal Digital Assistants).
The present invention is made to solve the problems, and its object is to provide a 2D/3D switching type liquid crystal display panel and a 2D/3D switching type liquid crystal display device, each of which allows the viewing angle during the 2D display to be as wide as that in the 2D-only display. Another object of the present invention is to improve reliability against the dropping and the impact.